      (fn
        ([o] (apply f o x y more))
        ([o z] (apply f o x y z more))
-       ([o z & args] (apply f o x y z (concat more args))))))
+       ([o z & args] (apply f o x y z (cc/concat more args))))))
 
 (defn mjuxt
   "Return a function which calls each function in `fs` on the

  ([f coll] (reductions f (f) coll))
  ([f init coll]
     (let [sentinel (Object.)]
       (->> (r/mapcat identity [coll [sentinel]])
            (tr/map-state (fn [acc x]
                            (if (identical? sentinel x)
                              [nil acc]

`r/reduce`."
  ([keyfn f coll]
     (let [sentinel (Object.)]
       (->> (concat coll [sentinel])
            (tr/map-state (fn [[k acc] x]
                            (if (identical? sentinel x)
                              [nil acc]
